[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172340
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
640 PM EST SAT DEC 17 2016

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURE...

A strong cold front is moving southward through Texas. The front
will enter the western Gulf of Mexico around 06Z on Sunday
morning. Strong high pressure over the plains states will drive
the front quickly southward through the western Gulf. North winds
are expected to rapidly reach gale force over the western Gulf of
Mexico behind the front beginning on Sunday morning. The gale-
force winds will become confined to the southwestern Gulf of
Mexico by Sunday night. The cold front will be positioned over the
Gulf from 30.5N87W to 24N96W to 21N97W at 18Z on Sunday. Expect N
gale-force winds and sea heights of 8 to 11 feet, to the NW of the
cold front at that time. Please read the Atlantic high seas
forecast, that is listed under AWIPS/WMO headers MIAHSFAT2/FZNT02
KNHC, for more details.

...THE ITCZ/MONSOON TROUGH...

The monsoon trough extends westward from the African coast from
Sierra Leone near 08N12W to 04N19W. The ITCZ continues from 04N19W
to 03N41W and 04N46W to 03N50W. Convective precipitation:
Scattered moderate and isolated strong from 03N to 07N between
15W and 30W.

...DISCUSSION...

...THE GULF OF MEXICO...

Upper level SW wind flow spans the entire Gulf of Mexico. SE to S
return flow covers the entire gulf. W of 90W the return flow is
fresh to strong. The stage is being set for the arrival of a cold
front on Sunday morning which will usher in gale-force winds
behind it. Please read the SPECIAL FEATURES section for more
details. After the cold front reaches the southwestern Gulf, it is
expected to become stationary from Louisiana southwestward over
the Bay of Campeche. Light to moderate E to SE winds will prevail
over the Gulf of Mexico on Monday and Tuesday to the east of the
front.

...THE CARIBBEAN SEA...

A weak upper-level trough over central America is triggering some
isolated convection over the far SW Caribbean. Otherwise, the
basin resides beneath dry W to NW upper-level wind flow. A
persistent ridge of high pressure over the western Atlantic waters
is teaming up with low pressure over Colombia to support fresh to
strong NE to E winds N of the coasts of Colombia and Venezuela.
This area of winds will amplify and expand northward and across
the southwest and eastern Caribbean tonight through Monday as the
ridge shifts eastward over the western Atlantic waters. Winds just
N of the coast of Colombia will reach gale force on Monday before
the gradient of pressure between the ridge and low over Colombia
begins to relax. Otherwise, gentle to moderate NE to E flow will
continue over the NW Caribbean waters through Monday.

...HISPANIOLA...

Deep-layer high pressure will maintain a relatively quiet weather
pattern over the island for the next several days. Subsident air
aloft will produce drying over the area tonight through Tuesday.

...THE ATLANTIC OCEAN...

A weakening stationary front extends SW from 32N42W to 25N58W to
24N79W. An area of fresh to strong NE to E winds is present along
and up to 150 nm north of this front. Convection associated with
this front has diminished as it continues to weaken. High pressure
centered near the Azores will be reinforced by a new cell moving
eastward from north America. The resultant ridge will continue to
dominate the remainder of the Central and Eastern Atlantic. The
next cold front moving eastward from the United States on Monday
and Tuesday is expected to be weaker than its predecessor and is
not anticipated to pass to the S of 32W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
McElroy
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